Clark could not recall any specific extreme political views Hodgkinson may have held. Sen. Bernie Sanders later said Hodgkinson had volunteered on his campaign, and Sanders condemned the shooting.

"He could get heated about things he was interested in," Clark recalled. "He was not stupid by any means."

Hodgkinson was charged in April 2006 with battery and aiding damage to a motor vehicle but the charges were later dismissed, records show.

The Associated Press reported the FBI believes Hodgkinson had been in the Alexandria area since March, living out of a van and not working.

Hodgkinson apparently wrote many letters to the editor of his local newspaper, the Belleville News-Democrat, which published nearly two dozen of them between 2010 and 2012. Many included complaints about income inequality, the AP reported.

At the time of the shooting, the congressmen were practicing for the congressional baseball game, an annual bipartisan event that raises money for charity. This year’s game, scheduled for Thursday, the supported charities are the Boys & Girls Clubs of Greater Washington, the Washington Nationals Dream Foundation and the Washington Literacy Center.